1. Field of the Invention
The present invention relates to a method of a focus error signal adjustment in an optical disk device, which shapes a S-shaped focus error signal used for carrying out a focus servo and which adjusts an amplitude and S-shaped balance of the signal, and the optical disk device thereof.
2. Description of the Related Art
Conventionally, in an optical disk device, a focus error signal is generated, on the basis of a laser beam reflected on a data recording layer, by irradiating the laser beam on the data recording layer of the optical disk. Here, the focus error signal is a signal obtained by changing a focus position of the laser beam. When generating the focus error signal, the focus servo is carried out on the basis of the signal. The focus servo enables the focus to be in an appropriate position on the optical disk, and then enables an accurate reading and recording of a data. Thus, a regular waveform of the focus error signal without an error is necessary.
Consequently, a disk player is well-known in that it generates the focus error signal by changing the focus position of an optical pickup, with the optical disk remaining still, so that the waveform of the focus error signal is well-balanced, and that then adjusts a S-shaped curve of the signal to be axisymmetrical with centering on a reference level (refer to Japanese Laid-Open Patent Publication No. 2001-222826, for example).
Also, an optical disk recording/playing method is well-known in that when recording and playing the optical disk, it adjusts the focus position so that an emboss pit data is played optimally in an adjustment area, which has emboss pit rows, for an accurate data record/play while maintaining an optimal focus condition, and afterward, it determines a focus detection error occurred in a land portion in a space, and when recording and playing in the land portion or a groove portion, the focus position is controlled by correcting the focus detection error determined in the optimal focus position in the emboss pit data (refer to Japanese Laid-Open Patent Publication No. 2003-233915, for example).
However, a technique described in the Patent Publication No. 2001-222826 cannot prevent a problem that when the emboss pit to which a CAPA (Complementary Allocated Pit Address) is allocated is in a land track and a groove track in the optical disk, an error occurs in the waveform of the focus error signal due to the emboss pit. Also, a technique described in the Patent Publication No. 2003-233915 cannot enable a formation of the waveform by increasing and decreasing an amplitude of the focus error signal and by making the waveform of the focus error signal be symmetrical with respect to a reference point.